Motor

Abstract

The present invention provides a motor. The motor comprises: an armature having a rotating shaft; a first bearing portion located on one axial side; a second bearing portion located on the other axial side; a frame assembly having a frame and a magnet for holding the first bearing portion and the second bearing portion; a force applying structure for applying force to the rotating shaft from one of the second bearing portion and the first bearing portion toward the other by magnetic force, the second bearing portion being a metal bearing, the force applying structure being between the armature and the second bearing portion along the axial direction, and having a magnet and a sliding member arranged on the rotating shaft, the sliding member being arranged between the magnet arranged on the rotating shaft and the second bearing portion.

Description

[0001] This application is a divisional application of the patent application with application number 201611150051.8, application date December 13, 2016, and invention name inner rotor type motor. Technical Field

[0002] The present invention relates to a motor, and in particular to an inner rotor type motor capable of maintaining a rotation position. Background Art

[0003] Inner rotor type motors are often used as driving sources for office equipment and household electrical appliances, for example. Some inner rotor type motors are used for applications where the rotation position of a device mounted on the motor rotating shaft needs to be maintained.

[0004] The following patent document 1 discloses a structure of an inner rotor type motor, in which a brake member on the fixed side and a brake member on the movable side for performing a braking action are built into a housing, and a stopping holding torque can be obtained when power is not supplied. In this structure, the brake is made to operate in a non-powered state by utilizing the gravitational force generated by the positional misalignment between the magnetic center of a magnet on the housing side and the axial center of the rotor.

[0005] The following patent document 2 discloses a device structure in which a braking force and a holding force are obtained by arranging a multi-pole magnetized magnet having a plurality of magnetic poles on one side of a rotor side and a stator side on the outside of a motor frame, and arranging a multi-pole magnetized magnet having a plurality of magnetized portions and a plurality of hysteresis portions on the other side of a rotor side and a stator side facing the multi-pole magnetized magnet.

[0006] Furthermore, Patent Document 3 listed below discloses a structure in which a valve opening and closing device used in an exhaust gas recirculation device or the like has a return spring for closing the valve.

[0007] Patent Document 4 listed below discloses a structure of a spindle drive device having a built-in braking device, in which a braking coil spring is arranged axially outside a motor.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2001-320856

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 10-150762

[0012] Patent Document 3: Japanese Patent Application Publication No. 2011-211825

[0013] Patent document 4: German patent application publication DE102008061117A1

[0014] However, in an apparatus (equipment) that uses an inner rotor type motor as described above to displace a component, when it is necessary to maintain the rotational position of the motor corresponding to the position of the component, a holding mechanism is usually provided near the target component in the apparatus. However, in an apparatus having a structure that displaces a component after decelerating the rotational speed of the motor using a speed reduction mechanism composed of gears, etc., when a holding mechanism is provided after the motor passes through the speed reduction mechanism, a large holding force must be exerted by the holding mechanism. Therefore, in such a case, a holding mechanism with large size and structural specifications needs to be provided, which results in a large-scale apparatus using an inner rotor type motor or an increase in manufacturing cost.

[0015] When a brake mechanism is provided inside the motor as described in Patent Document 1, the motor's holding force increases accordingly with the reduction ratio, and thus the holding mechanism can be simplified. However, the structure described in Patent Document 1 has a large number of parts and a complex structure in which a partition cover is provided inside the motor, which increases the manufacturing cost. In addition, the force that generates the friction holding force when no power is supplied is only the magnetic thrust of the rotor, and therefore, it is difficult to obtain a high holding force. In the case of expecting a high holding force, a strong magnet has to be used, which has a problem in terms of high cost.

[0016] The structure described in Patent Document 2 has a problem that a magnet is provided on the outside of the motor, etc., which is difficult to handle. In addition, it is necessary to make a magnet with uneven thickness, which is a manufacturing obstacle especially when miniaturization is desired. In addition, since a multi-pole magnet is formed on the rotating side and a multi-pole magnet is formed on the fixed side, vibration may be generated in the thrust direction.

[0017] Patent Documents 3 and 4 do not disclose effective measures for the above-mentioned problems. Summary of the invention

[0018] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an inner rotor type motor capable of holding a rotational position with a high holding force, with a simple and miniaturized structure.

[0019] In order to achieve the above-mentioned purpose, according to a technical solution of the present invention, an inner rotor type motor includes: an armature assembly, which includes a rotating shaft, an armature part installed on the rotating shaft, and a pressing part; a frame assembly, which has a frame for accommodating the armature part, a first bearing part located on one axial side of the armature part, and a second bearing part located on the other axial side of the armature part; and a force applying structure, which applies force to the rotating shaft in a direction away from the second bearing part, thereby pressing the pressing part toward the first bearing part.

[0020] Preferably, a support member is fixed to a portion of the rotating shaft between the second bearing and the armature, the urging structure includes a coil spring compressed between the support member and the second bearing, and the pressing portion is pressed toward the first bearing by the coil spring.

[0021] Preferably, the coil spring is mounted on the support member; and a pressing member is provided between the coil spring and the second bearing portion so as to be displaceable in the axial direction, and the coil spring presses the pressing member against the second bearing portion.

[0022] Preferably, the coil spring is attached to the frame assembly, and a pressing member is provided between the coil spring and the support member so as to be displaceable in the axial direction, and the coil spring presses the pressing member against the support member.

[0023] Preferably, a supporting member is fixed at a position between the second bearing portion and the armature portion in the rotating shaft, and the force structure includes a first force magnet arranged on the supporting member side and a second force magnet arranged facing the first force magnet and at a position closer to the second bearing portion than the first force magnet, and the pressing portion is pressed toward the first bearing portion by the repulsive force generated between the first force magnet and the second force magnet.

[0024] Preferably, the first urging magnet is disposed on the support member, and the second urging magnet is disposed on the support member so as to be displaceable in the axial direction and is pressed against the second bearing portion by a repulsive force.

[0025] Preferably, the inner rotor type motor is a brushed motor, and the supporting member is a commutator.

[0026] Preferably, the inner rotor type motor further includes a sliding washer which is arranged between the second bearing portion and the support member and is rotatable about the rotation axis relative to the second bearing portion.

[0027] Preferably, the pressing portion is pressed against the first bearing portion via a sliding washer.

[0028] According to the above invention, it is possible to provide an inner rotor type motor capable of retaining a rotational position with a high retaining force with a simple and downsized structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a side cross-sectional view showing an inner rotor type motor according to a first embodiment of the present invention.

[0030] Figure 2 It is a side cross-sectional view showing an inner rotor type motor according to a second embodiment.

[0031] Figure 3 It is a side cross-sectional view showing an inner rotor type motor according to a third embodiment.

[0032] Figure 4 This is a side view of the commutator according to the third embodiment as viewed from the axial direction.

[0033] Description of Reference Numerals

[0034] 1, 201, 301: inner rotor type motor; 1a, 201a: frame assembly; 1b, 201b, 301b: armature assembly; 2: rotating shaft; 2a: pressing portion; 10: frame; 21, 221: first bearing portion; 26, 226: second bearing portion; 30, 330: commutator (an example of a supporting member); 40, 240, 340: force structure; 41: coil spring; 51: gasket; 56: gasket (an example of a pressing member); 61, 66: sliding gasket; 230: commutator (an example of a pressing portion); 235: supporting member; 250: fixing member; 341: first force magnet; 342: second force magnet (an example of a pressing member). DETAILED DESCRIPTION

[0035] Hereinafter, an inner rotor type motor according to an embodiment of the present invention will be described.

[0036] [First embodiment]

[0037] Figure 1 It is a side cross-sectional view showing an inner rotor type motor 1 according to a first embodiment of the present invention.

[0038] exist Figure 1 In the diagram, the left-right direction is sometimes referred to as the axial direction.

[0039] like Figure 1 As shown, an inner rotor type motor (hereinafter, sometimes simply referred to as a motor) 1 generally includes a frame assembly 1a and an armature assembly (hereinafter, sometimes simply referred to as an armature) 1b rotatably supported on the frame assembly 1a. The motor 1 is a so-called brushed DC motor.

[0040] The armature assembly 1 b includes a rotating shaft 2 , an armature portion 4 , a commutator 30 , and the like.

[0041] The armature unit 4 is attached to the rotating shaft 2. The armature unit 4 includes an armature core 5 having a plurality of salient poles protruding in the radial direction, a winding (not shown) wound around each salient pole, and the like.

[0042] The commutator 30 is provided near one end portion (near the bottom) of the rotating shaft 2. The commutator 30 has segments (not shown) connected to the windings.

[0043] The frame assembly 1 a includes a frame 10 , a bracket 12 , a cover plate 13 , a magnet 8 , and the like.

[0044] The frame 10 has an end portion ( Figure 1 The left side of the frame 10 (sometimes called the top) is blocked in a cylindrical shape, and the rotating shaft 2 protrudes from this end. The other end of the frame 10 ( Figure 1 The opening of the frame 10 (the right end in the middle; sometimes referred to as the bottom) is blocked by the cover plate 13. The armature 1b is accommodated inside the frame 10, and the cover plate 13 constitutes the bottom of the frame 10, thereby constituting a housing in which the armature part 4 is accommodated. One end of the rotating shaft 2 protrudes from the top of the frame 10. The power of the motor 2 can be extracted to the outside from the protruding portion of the rotating shaft 2.

[0045] The first bearing portion 21 is held at the center of the top of the frame 10. The second bearing portion 26 is held at the center of the cover plate 13. That is, the first bearing portion 21 is located on one axial side of the armature portion 4, and the second bearing portion 26 is located on the other axial side of the armature portion 4. The rotating shaft 2 is axially supported by two bearings, namely the first bearing portion 21 and the second bearing portion 26 (sometimes referred to as bearings 21 and 26). The armature 1b is held rotatable relative to the frame 10 by the bearings 21 and 26.

[0046] The cover plate 13, the bracket 12, the second bearing portion 26, and the terminals and brushes (not shown) constitute the bracket unit 20. That is, the bracket 12 is mounted on the inner side of the cover plate 13. The bracket 12 holds a terminal to which current is supplied from the outside. The brush is connected to the top end of the terminal. The brush is arranged so that the front end thereof contacts the commutator 30 of the armature 1b. The motor 1 is driven by supplying power to the commutator segments on the commutator 30 via the brush.

[0047] In the present embodiment, the motor 1 has a force applying structure 40 for applying force to the rotating shaft 2 in one direction in the axial direction. The force applying structure 40 is provided inside the frame assembly portion 1a of the motor 1 between the second bearing portion 26 and the armature portion 4. A pressing portion 2a is provided at a portion of the rotating shaft 2 between the armature portion 4 and the first bearing portion 21, and the pressing portion 2a has a larger diameter than a portion of the rotating shaft 2 supported by the first bearing portion 21. A gasket 51 is arranged at a position closer to the first bearing portion 21 than the pressing portion 2a. The gasket 51 can rotate together with the rotating shaft 2. In addition, the gasket 51 can be pressed into the rotating shaft 2 or nested in the rotating shaft 2 in a dynamic fit (clearance fit) manner. The force applying structure 40 applies force to the rotating shaft 2 in a direction away from the second bearing portion 26 ( Figure 1 As a result, the pressing portion 2a and the gasket 51 are pressed toward the first bearing portion 21 together.

[0048] The biasing structure 40 includes a coil spring 41 and a washer (an example of a pressing member) 56. The coil spring 41 is arranged between the second bearing portion 26 and the commutator 30 that functions as a supporting member when biasing the rotating shaft 2. The washer 56 is arranged between the coil spring 41 and the second bearing portion 26. The washer 56 is nested in the rotating shaft 2 in a loose fit manner, and is arranged to be displaceable in the axial direction.

[0049] The coil spring 41 is arranged in such a manner that the coil axis is substantially consistent with the axial direction. The coil spring 41 is installed between the commutator 30 and the gasket 56 in a compressed state. In addition, in the present embodiment, a groove portion 33 is formed on the end surface on the second bearing portion 26 side of the commutator 30, and a part of the coil spring 41 is buried in the groove portion 33 along the axial direction. One axial end portion of the coil spring 41 is buried in the groove portion 33. In this way, since the coil spring 41 is arranged in the groove portion 33, the space required for arranging the coil spring 41 inside the motor 1 can be saved, thereby reducing the axial dimension of the motor 1. The coil spring 41 is thus installed on the commutator 30, and therefore rotates together with the rotating shaft 2 and the commutator 30.

[0050] The coil spring 41 has a tendency to expand from a compressed state between the commutator 30 and the washer 56. This restoring force has an effect of increasing the distance between the commutator 30 and the washer 56. That is, the coil spring 41 uses the restoring force to press the pressing portion 2a together with the washer 51 toward the first bearing portion 21. In addition, the coil spring 41 uses the restoring force to press the washer 56 toward the second bearing portion 26.

[0051] A sliding washer 61 is arranged between the first bearing portion 21 and the washer 51. The sliding washer 61 is nested on the rotating shaft 2 in a movable fit. The sliding washer 61 is rotatable relative to the rotating shaft 2 around the rotating shaft 2, and is rotatable relative to the first bearing portion 21 around the rotating shaft 2, and is displaceable in the axial direction. The washer 51 is pressed against the first bearing portion 21 via the sliding washer 61. In addition, instead of using only one sliding washer 61, a plurality of sliding washer 61 may be used.

[0052] A sliding washer 66 is arranged between the second bearing portion 26 and the washer 56. The sliding washer 66 is embedded in the rotating shaft 2 in a movable fit. The sliding washer 66 is rotatable relative to the rotating shaft 2 around the rotating shaft 2, and is rotatable relative to the second bearing portion 26 around the rotating shaft 2, and is displaceable in the axial direction. The washer 56 is pressed against the second bearing portion 26 via the sliding washer 66. In addition, the sliding washer 61 may not be used only one, but may be used in plurality.

[0053] The bearings 21 and 26 are, for example, metal bearings (oil-containing bearings). The end faces of the bearings 21 and 26 on the side of the armature portion 4 have smooth surfaces perpendicular to the rotating shaft 2. The sliding washer 61 can slide around the rotating shaft 2 relative to the end face of the first bearing portion 21 and the washer 51 in a state of being clamped by the first bearing portion 21 and the washer 51. Similarly, the sliding washer 66 can slide around the rotating shaft 2 relative to the end face of the second bearing portion 26 and the washer 56 in a state of being clamped by the second bearing portion 26 and the washer 56.

[0054] Thus, in this embodiment, a biasing structure 40 using a coil spring 41 is arranged on the armature 1b side, and an axial thrust load is applied to the first bearing portion 21 and the second bearing portion 26 by the biasing structure 40. Thus, a holding torque for the rotation of the armature 1b can be obtained by using a friction force corresponding to the applied load, the friction coefficient of the surface receiving the thrust load, and the area of ​​the surface. That is, a holding torque generated by static friction and a holding torque generated by loss torque can be obtained between the end surface of the first bearing portion 21 and the sliding washer 61, between the sliding washer 61 and the washer 51, between the washer 56 and the sliding washer 66, and between the sliding washer 66 and the end surface of the second bearing portion 26. In a state where no torque is applied, the rotation position of the armature 1b can be maintained by using the influence of such a holding torque to overcome the external force applied to the rotating shaft 2.

[0055] When the motor 1 rotates, the sliding washer 61 slides relative to the end surface of the first bearing portion 21 and the washer 51 around the rotating shaft 2. In addition, the sliding washer 66 slides relative to the end surface of the second bearing portion 26 and the washer 56 around the rotating shaft 2. Therefore, the motor 1 can rotate smoothly. In addition, the components that slide relative to the sliding washers 61 and 66 may not be all of the bearings 21 and 26, the washers 51 and 56, and may be appropriately changed according to the rotation state of the motor 1.

[0056] By providing a simple structure such as the coil spring 41, washers 51, 56, and sliding washers 61, 66 inside the motor 1, it is possible to generate a holding torque of the motor 1. Since the structure of the motor 1 can be simplified, the manufacturing cost of the motor 1 can be reduced. In many applications where the motor 1 is decelerated by a reducer or the like, a smaller holding torque can be generated on the motor 1 side to generate an equivalent holding force compared to the case where a holding mechanism is provided after deceleration. Therefore, the structure of the system using the motor 1 can be miniaturized or simplified. In addition, the reliability of the system using the motor 1 can be improved.

[0057] [Second embodiment]

[0058] The basic structure of the motor of the second embodiment is the same as that of the first embodiment, and therefore, the description thereof will not be repeated here. Components having the same functions as those of the first embodiment are marked with the same reference numerals as those of the first embodiment, and the detailed description is sometimes omitted. The force-applying structure includes a coil spring and a gasket, which is also the same as the first embodiment. In the second embodiment, the position of the force-applying structure, the direction of the force, etc. are different from those of the first embodiment. In the second embodiment, the coil spring is provided on the fixed body side, i.e., the frame assembly body side.

[0059] Figure 2 It is a side cross-sectional view showing an inner rotor type motor 201 according to the second embodiment.

[0060] exist Figure 2 In the drawings, the left-right direction is sometimes referred to as an axial direction. The motor 201 includes a frame assembly 201a and an armature 201b.

[0061] like Figure 2 As shown, in the frame assembly 201a, the second bearing 226 is held at the center of the top of the frame 10. On the contrary, the first bearing 221 is held at the center of the cover plate 13. The rotating shaft 2 of the armature 201b is axially supported by the first bearing 221 and the second bearing 226.

[0062] A fixing member 250 is fixed inside the top of the frame 10. A groove 253 is formed on the fixing member 250, similar to the groove 33 of the first embodiment, in which the coil spring 41 is embedded. The groove 253 is formed in an annular shape substantially coaxial with the rotating shaft 2 so as to open toward the first bearing 221.

[0063] One axial end portion of the coil spring 41 is embedded in the groove portion 253. That is, the coil spring is attached to the frame assembly 201a so as not to rotate relative to the frame assembly 201a.

[0064] In the second embodiment, the armature 201 a includes a commutator 230 and a support member 235 having different structures from those of the first embodiment.

[0065] The commutator 230 is different from the commutator 30 of the first embodiment in that it does not have the groove portion 33 and does not have the coil spring 41 embedded therein. The commutator 230 functions as a pressing portion that is pressed against the first bearing portion 221 when a force is applied to the rotating shaft 2 as described later. A gasket 51 is arranged at a position closer to the first bearing portion 221 than the commutator 230. The gasket 51 can rotate together with the rotating shaft 2. In addition, the gasket 51 can be pressed into the rotating shaft 2 or can be arranged in a movable fit in the rotating shaft 2.

[0066] The support member 235 is disposed between the armature portion 4 and the second bearing portion 226. The support member 235 includes a thrust frame 238 protruding from the armature portion 4 toward the top side and the bearing member 236.

[0067] The bearing member 236 is, for example, a sintered oil-impregnated metal bearing. The thrust frame 238 is, for example, made of resin and connected to the armature portion 4. The bearing member 236 is pressed onto the rotating shaft 2. The thrust frame 238 and the bearing member 236 rotate together with the rotating shaft 2. The thrust frame 238 has a bowl shape that opens toward the second bearing portion 226, and the bearing member 236 is arranged inside the thrust frame 238. The outer periphery of the bearing member 236 is covered by the thrust frame 238, so that the oil contained in the bearing member 236 can be prevented from splashing due to the centrifugal force when the armature 201b rotates.

[0068] In the second embodiment, the biasing structure 240 includes a coil spring 41 and a washer (an example of a pressing member) 56 mounted on the fixing member 250. The washer 56 is arranged between the coil spring 41 and the bearing member 236 of the support member 235. The washer 56 is nested on the rotating shaft 2 in a dynamic fit manner and is arranged to be displaceable in the axial direction. The coil spring 41 is installed in a compressed state between the support member 235 and the fixing member 250 (that is, between the support member 235 and the second bearing portion 226).

[0069] The biasing structure 240 uses the restoring force of the coil spring 41 to bias the rotating shaft 2 in a direction away from the second bearing portion 226 ( Figure 2 That is, the coil spring 41 presses the commutator 230 together with the washer 51 toward the first bearing portion 221. In addition, the coil spring 41 presses the washer 56 toward the bearing member 236.

[0070] The sliding washer 61 is arranged between the first bearing portion 221 and the washer 51 in the same manner as in the first embodiment. That is, the commutator 230 is pressed against the first bearing portion 221 via the sliding washer 66. The sliding washer 61 can slide relative to the end surface of the first bearing portion 221 and the washer 51 around the rotating shaft 2 in a state of being sandwiched between the first bearing portion 221 and the washer 51. In addition, the sliding washer 66 is arranged between the bearing member 236 and the washer 56 in the same manner as in the first embodiment. The sliding washer 66 can slide relative to the end surface of the bearing member 236 and the washer 56 around the rotating shaft 2 in a state of being sandwiched between the bearing member 236 and the washer 56. That is, in a state where the washer 51 and 56 are respectively urged by the urging structure 240, the sliding washer 61 is between the first bearing portion 221 and the washer 51, and the sliding washer 66 is between the bearing member 236 and the washer 56, and the same action as in the first embodiment is produced.

[0071] Thus, in the second embodiment, the biasing structure 240 using the coil spring 41 is arranged on the frame assembly 201a side, and the biasing structure 240 applies an axial thrust load to the first bearing portion 221 and the bearing member 236. Therefore, a holding torque generated by static friction and a holding torque generated by loss torque are obtained between the end surface of the first bearing portion 221 and the sliding washer 61, between the sliding washer 61 and the washer 51, between the washer 56 and the sliding washer 66, and between the sliding washer 66 and the end surface of the bearing member 236. Therefore, the same effect as that of the first embodiment can be obtained in the second embodiment as well.

[0072] In the second embodiment, since the coil spring 41 is disposed on the fixed body side, the commutator 230 can be configured with a simpler structure.

[0073] [Third Embodiment]

[0074] The basic structure of the motor of the third embodiment is the same as that of the first embodiment, and therefore, the description thereof will not be repeated here. Components having the same functions as those of the first embodiment are marked with the same reference numerals as those of the first embodiment, and the specific description thereof is sometimes omitted. The third embodiment differs from the first embodiment in that a group of force magnets is used to form a force structure.

[0075] Figure 3 It is a side cross-sectional view showing an inner rotor type motor 301 according to the third embodiment.

[0076] exist Figure 3 In the axial direction, the left and right direction is sometimes called the axial direction. Figure 3 As shown, the motor 301 includes a frame assembly 1a and an armature 301b having the same structure as the first embodiment. Figure 3 The structure of the left side in FIG. 1 is the same as that of the first embodiment.

[0077] In the armature 301 b , a commutator 330 is used instead of the commutator 30 . The commutator 330 is fixed to the rotating shaft 2 .

[0078] In the third embodiment, the motor 1 has a force applying structure 340 for applying force to the rotating shaft 2 in one direction in the axial direction. The force applying structure 340 is provided between the second bearing portion 26 and the armature portion 4 inside the frame assembly portion 1a. The force applying structure 340, like the force applying structure 40 in the first embodiment, applies force to the rotating shaft 2 in a direction away from the second bearing portion 26 ( Figure 3 As a result, the pressing portion 2a is pressed toward the first bearing portion 21 together with the gasket 51.

[0079] More specifically, the urging structure 340 is disposed between the commutator 330 and the second bearing portion 26. When the urging structure 340 urges the rotating shaft 2, the commutator 330 functions as a supporting member.

[0080] The urging structure 340 includes a first urging magnet 341 disposed on the commutator 330 side and a second urging magnet 342 disposed on the second bearing 26 side relative to the first urging magnet 341. Both the first urging magnet 341 and the second urging magnet 342 are permanent magnets magnetized into two polarities in the axial direction.

[0081] The commutator 330 has a protrusion 333 protruding in the axial direction from the end surface on the side of the second bearing portion 26. The first urging magnet 341 and the second urging magnet 342 are arranged on the commutator 330 in such a manner that the protrusion 333 penetrates a hole provided in the center of the first urging magnet 341 and the second urging magnet 342. The first urging magnet 341 and the second urging magnet 342 are arranged in such a manner that the same poles face each other.

[0082] Figure 4 This is a side view of the commutator 330 according to the third embodiment as viewed from the axial direction.

[0083] like Figure 4 As shown, the commutator 330 is formed into a substantially cylindrical shape, including a cylindrical portion 330a having a lateral surface on which commutator segments (not shown) are arranged, and a commutator vertical segment 330b around which a coil conductor connected to each commutator segment is wound. In the third embodiment, the protrusion 333 protruding from the cylindrical portion 330a has a polygonal prism shape such as a hexagonal prism. The first urging magnet 341 and the second urging magnet 342 have a polygonal hole portion such as a hexagon matching the shape of the protrusion 333, and the hole portion has a size that can be embedded in the protrusion 333 in a movable fit. As a result, the first urging magnet 341 and the second urging magnet 342 are both installed on the commutator 330 in a state that they can be displaced in the axial direction and can rotate together with the commutator 330. In addition, the first urging magnet 341 can also be pressed into the protrusion 333.

[0084] Back to Figure 3 The first urging magnet 341 is supported by the end surface of the cylindrical portion 330 a of the commutator 330 . In addition, a sliding washer 66 is disposed between the second urging magnet 342 and the end surface of the second bearing portion 26 .

[0085] Since the first urging magnet 341 and the second urging magnet 342 are arranged in a manner that the same poles face each other, a magnetic repulsive force acts between the two. The urging structure 340 uses the repulsive force to press the pressing portion 2a and the gasket 51 toward the first bearing portion 21 via the sliding gasket 61. In addition, the urging structure 340 uses the repulsive force to press the second urging magnet 342 itself toward the second bearing portion via the sliding gasket 66. The end face of the second urging magnet 342 on the second bearing portion 26 side has a smooth surface perpendicular to the axial direction.

[0086] The sliding washer 61 can slide around the rotating shaft 2 with respect to the end surface of the first bearing 21 and the washer 51 respectively in a state of being clamped by the first bearing 21 and the washer 51. In addition, the sliding washer 66 can slide around the rotating shaft 2 with respect to the end surface of the second bearing 26 and the end surface of the second urging magnet 342 respectively in a state of being clamped by the second bearing 26 and the second urging magnet 342. That is, in a state where the urging structure 340 is used to urge the urging washer 51 and the second urging magnet 342 respectively, the sliding washer 61 is between the first bearing 21 and the washer 51, and the sliding washer 66 is between the second bearing 26 and the second urging magnet 342, and the same action as the first embodiment is produced.

[0087] Thus, in the third embodiment, the urging structure 340 that can generate the repulsive force between the same magnetic pole surfaces of the urging magnets 341 and 342 is used to apply an axial thrust load to the first bearing portion 21 and the second bearing portion 26. Therefore, between the end surface of the first bearing portion 21 and the sliding washer 61, between the sliding washer 61 and the washer 51, between the second urging magnet 342 and the sliding washer 66, and between the sliding washer 66 and the end surface of the second bearing portion 26, a holding torque generated by static friction and a holding torque generated by loss torque can be obtained. Therefore, in the third embodiment, the same effect as that of the first embodiment can also be obtained.

[0088] In the third embodiment, since the coil springs as in the first and second embodiments are not used, the structure can be simplified, and the number of steps required to manufacture the motor 1 can be reduced. Furthermore, by generating the preload force in a non-contact manner, the possibility of abnormal noises caused by the coil springs can be reduced.

[0089] [other]

[0090] An inner rotor type motor can be formed by appropriately combining the characteristic parts of the above-mentioned embodiments. In either case, by adopting a structure in which the pressing portion of the armature assembly is pressed against the first bearing portion using a force structure, the rotation position can be maintained in a motor with a simple structure. For example, in a structure in which the force structure does not rotate with the rotation of the rotating shaft as in the above-mentioned second embodiment, a structure composed of a pair of force magnets as in the third embodiment can also be adopted as the force structure. Specifically, in a motor having a structure as in the second embodiment, it is sufficient to mount the second force magnet on a fixed member mounted on the frame assembly, and to enable the first force magnet to be displaced axially and pressed against the supporting member under the repulsive force between the force magnets. Thus, the commutator can be pressed against the first bearing portion through the sliding gasket, thereby generating a retaining torque. In addition, by using a polygonal dynamic fit as in the above-mentioned second embodiment, the first force magnet can be prevented from rotating relative to the fixed member around the rotating shaft, thereby generating a retaining torque between the supporting member and the first force magnet.

[0091] Also can replace sliding pad, and use other sliding member.In addition, also can not use sliding pad etc., but make the 1st bearing part and the pressing part of armature assembly face each other, or make the 2nd bearing part and pressing member face each other.

[0092] In the above-mentioned first embodiment and third embodiment, the force-applying structure can be installed on the bracket and the cover plate side in a manner that does not rotate with the commutator and does not rotate relative to the frame assembly. In the case of using a force-applying structure using a coil spring, by using a coil spring to press a pressing member such as a gasket against the end face of the commutator, the pressing portion of the armature assembly is pressed against the first bearing portion, and a holding torque can be generated in the same manner as in the second embodiment. In addition, in the case of using a force-applying structure using a pair of force-applying magnets, by pressing a first force-applying magnet configured to be non-rotatable relative to the frame assembly and displaceable in the axial direction against the end face of the commutator, the pressing portion of the armature assembly is pressed against the first bearing portion, and a holding torque can be generated in the same manner as in the second embodiment.

[0093] The force-applying structure is not limited to the structure using a coil spring or a structure using a force-applying magnet as in the above-mentioned embodiment. Various structures can be used to press the rotating shaft against the first bearing member. For example, the force-applying structure can be formed using springs of other forms, or the force-applying structure can be formed in a manner that uses magnetic attraction to apply force to the rotating shaft.

[0094] The motor is not limited to the above-mentioned brushed inner rotor type motor, and may be another type of inner rotor type motor such as a brushless inner rotor type motor.

[0095] All elements in the above-mentioned embodiments are illustrative only and should not be construed as limiting. The scope of the present invention is indicated by the claims rather than the above-mentioned description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A motor, characterized in that: include: an armature having a rotating shaft; A first bearing portion located on one axial side; A second bearing portion located at the other axial side; A frame assembly having a frame and a magnet for holding the first bearing portion and the second bearing portion; a biasing structure for biasing the rotating shaft from one of the second bearing portion and the first bearing portion toward the other by magnetic force, The second bearing portion is a metal bearing, The urging structure includes a magnet and a sliding member provided on the rotating shaft between the armature and the second bearing portion in the axial direction. The sliding member is located between the magnet provided on the rotating shaft and the second bearing portion. The sliding member is pressed toward the second bearing portion.

2. The motor according to claim 1, wherein: The sliding member is slidable relative to the second bearing portion and the magnet provided on the rotating shaft.

3. The motor according to claim 2, wherein: In response to the rotation of the armature, a retaining torque is generated between the sliding member and the second bearing portion.

4. The electric machine according to any one of claims 1 to 3, wherein: A support member for supporting a magnet disposed on the rotating shaft is fixed to the rotating shaft. A magnet provided on the rotating shaft is fixed to the supporting member.

5. The motor according to claim 4, wherein: A part of the supporting member is a polygonal column, A magnet provided on the rotating shaft is fixed to a portion of the supporting member.

6. The motor according to claim 4, wherein: The supporting member is a commutator.

7. The motor according to claim 5, wherein: A portion of the support member is a protrusion that protrudes toward the second bearing portion.

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